GENETICS AND EVOLUTION
INHERITANCE AND VARIATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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one sperm cell fertilizes one egg cell
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one sperm cell fertilizes one egg cell which then divides into two embryos
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one sperm cell fertilizes two egg cells
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two sperm cells fertilize two different egg cells
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Detailed explanation-1: -Two separate eggs (ova) are fertilised by two separate sperm, resulting in fraternal or ‘dizygotic’ (two-cell) twins. These babies will be no more alike than siblings born at separate times. The babies can be either the same sex or different sexes, with the odds roughly equal for each.
Detailed explanation-2: -Fraternal twins are formed when two eggs meet two sperm in the womb. Each is fertilized independently, and each becomes an embryo.
Detailed explanation-3: -Identical twins (also called monozygotic twins) result from the fertilization of a single egg by a single sperm, with the fertilized egg then splitting into two. Identical twins share the same genomes and are always of the same sex.
Detailed explanation-4: -Non-identical twins Non-identical (dizygotic) twins happen when 2 separate eggs are fertilised and then implant into the womb (uterus). These non-identical twins are no more alike than any other 2 siblings. Non-identical twins are more common. The babies may be of the same sex or different sexes.
Detailed explanation-5: -Sometimes a woman’s ovaries release 2 eggs, and a separate sperm fertilises each egg. This forms twins. These twins are called fraternal twins, dizygotic twins (meaning two zygotes) or non-identical twins.